ARM: dts: imx6sx-sdb: add i2c3 node

This patch adds node i2c bus 3 to get the appropriate userland device
file. So for prototyping it's possible to experiment within userland.
Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6sx-sdb.dtsi

@@ -184,6 +184,13 @@ &fec2 {
 	status = "okay";
 };
 
+&i2c3 {
+	clock-frequency = <100000>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_i2c3>;
+	status = "okay";
+};
+
 &i2c4 {
         clock-frequency = <100000>;
         pinctrl-names = "default";
@@ -378,6 +385,13 @@ MX6SX_PAD_GPIO1_IO00__I2C1_SCL		0x4001b8b1
 			>;
 		};
 
+		pinctrl_i2c3: i2c3grp {
+			fsl,pins = <
+				MX6SX_PAD_KEY_ROW4__I2C3_SDA		0x4001b8b1
+				MX6SX_PAD_KEY_COL4__I2C3_SCL		0x4001b8b1
+			>;
+		};
+
 		pinctrl_i2c4: i2c4grp {
 			fsl,pins = <
 				MX6SX_PAD_CSI_DATA07__I2C4_SDA		0x4001b8b1